In a mixing bowl, combine the Dijon mustard, Scanian mustard, and strong coarse-grained mustard.

Add honey, freshly ground black pepper, coffee, and smoky whiskey to the mustards.

Slowly whisk in the cooking oil in a thin stream until the sauce emulsifies and thickens.

Finely chop the dill, including the stems, and stir it into the mustard sauce.

Drain the clear-cured herring fillets and slice them into bite-sized pieces.

Add the sliced herring to the sauce and gently mix until all the pieces are well-coated.

Transfer the finished herring to a clean glass jar, seal it, and let it marinate in the refrigerator for at least two days before serving for the best flavor.